Vanguard Instruments ATRT-03 is a three-phase, transformer turns-ratio tester. The ATRT-03 is lightweight, rugged, and portable, and is designed for transformer testing at utility power substations.
It determines the transformer turns ratio by accurately measuring the voltages across the unloaded transformer windings and then displaying the ratio of these voltages (ratios range from 0.8 to 15,000). The ATRT-03A calibrates each measurement to ensure the turns-ratio accuracy.